Flashcards in biology chapter 7 Deck (69)
Loading flashcards...
1
nervous system
enables organisms to receive and respond to stimuli from their external and internal environments
2
neurons
are the functional units of the nervous system
3
dendrites
are cytoplasmic extensions that receive information and transmit it toward the cell body
4
cell body (soma)
contains the nucleus and controls the metabolic activity of the neuron
5
axon
is a long cellular process that transmits impulses away from the cell body
6
myelin
insulating substance that cover axons, which allow axons to conduct impulses faster
7
oligodendrocytes
produce myelin in the central nervous system
8
schwann cells
produce myelin in ther peripheral nervous sytem
9
nodes of Ranvier
the gaps between segments of myelin
10
synapse
or synaptic cleft, which is the fap between the axon terminals of one cell and the dendrites of the next cell
11
action potentials
impulses that travel the length of the axon and invade the nerve terminal, thereby causing the release of neurotransmitter into the synapse
12
resting potential
when a neuron is at rest, the potential difference between the extracellular space and the intracellular space
13
typical resting membrane potential
is -70 millivolts (mV) which means that the inside of the neuron is more negative than the outside
14
minimum threshold membrane potential
(usually around -50 mV) is the level at which an action potential is initiated
15
repolarization
returns the cell to a more negative potential
16
refractory period
immediately following an action potential, it may be very difficult or impossible to initiate another action potential
17
synapse
the gap between the axon terminal of one neuron and the dendrites of another neuron
18
neurotransmitters
the nerve terminal contains thousands of membrane bound vesicles full of chemical messengers
19
curare
blocks the post synaptic acetylcholine receptors so that acetylcholine is unable to interact with the receptor. This leads to paralysis by blocking nerve impulses to muscles
20
botulism toxin
prevents the release of acetylcholine from the presynaptic membrane and also results in paralysis
21
anti-cholinesterases
are used as nerve gases and in the insecticide Parathion. As the name implies, these substances inhibit the activity of the acetylcholinesterase enzyme. As a result the acetylcholine is not degraded in the synapse and continues to affect the post-synaptic membrane. therefore, no coordinated muscular contractions can take place
22
afferent neurons
neurons that carry sensory information about the external or internal environment to the brain or spinal cord
23
efferent neurons
neurons that carry motor commands from the brain or spinal cord to various parts of the body
24
plexus
a network of nerve fibers
25
ganglia
clusters of neuronal cell bodies
26
central nervous system
consists of the brain and spinal cord
27
brain
the brain is a mass of neurons that resides in the skull. Its functions include interpreting sensory information, forming motor plans, and cognitive function (thinking). The brain consists of an outer portion called the gray matter (cell bodies) and an inner white matter (myelinated axons). the brain can be divided into the forebrain, midbrain, and hindbrain)
28
forebrain (prosencephalon)
the forebrain consists of the telencephalon and the diencephalon
29
cerebral cortex
which is the highly convoluted gray matter that can be seen on the surface of the brain
30
